Horrifying images of the war in Iraq and Syria are helping to move British Muslims out of "complacency and passivity," which had caused hundreds of jihadists to take part in the conflict, a top British counter-terrorism police officer said according to the British daily newspaper The Guardian.

A drastic change in attitudes within communities was noticed in the past six weeks, the Metropolitan police’s head of specialist operations, Cressida Dick said.

The images from conflict zones were being "used to good effect" to challenge extremist preachers and to encourage the reporting of suspicious activities, she said during a lecture at the Royal United Services Institute.

People at risk of radicalization have been referred to the Channel program, Dick said adding that the program is a government scheme designed to stop vulnerable people being drawn into terrorism.

The British government is also taking other measures to limit the participation of citizens in the war in Syria.

Last week, it pressured YouTube to remove a video uploaded by man, born in Cardiff who is now in Syria, beckoning his fellow British Muslims to participate in the war in Syria.

The video, although posted in some news websites such as the Mail Online and The Telegraph, has since been taken down.

Almost 15,000 items promoting jihad had been taken down from the internet due to government pressure since December 2013.

Besides, Prime Minister, David Cameron, mentioned that more intelligence and security are being used to prevent people travelling to Syria and monitoring as well, when they return.

“The most important thing of all is to stop this radicalization in the first place. That's why my counter-extremism taskforce is about driving out the extremist, poisonous narrative and getting it out of our schools, getting it out of our universities, getting it out of our campuses, getting it out of our prisons, confronting it wherever it appears, because we know the end part of this extremist narrative can mean people dead on our own streets," Cameron said.